Earlier this year, a female Western Carpenter Bee bored a hole into my bird nest box and came back and forth for a while. In late June, she started rolling up the sawdust (or I guess the mandible-dust) into a ball (she was at it for several minutes, left, and came back to continue). Here is a full video taken from a camera I installed in the nest box: https://drive.google.com/file/d/1KNaAfP4CtqrEnw66V_BlriRlQ8C5y1L4/view?usp=sharing
Does anyone know why she is doing this? Insights are appreciated.
https://www.inaturalist.org/observations/292767265
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Do you know the species of plant that made the wood? I’m looking at a few sources (none scholarly) that have conflicting hypotheses. Many of them discuss the behavior of honey bees (Apini), which are completely different types of bees to carpenter bees (Xylocopinae).
I noticed that the bee in your nest box rolled along with the sawdust and at some points was “head down,” which could either bee a testament to their lack of ability to balance while not flying or its care for not being fully immersed in the dust. I imagine flying around with a lot of sawdust stuck to a bee’s setae can hamper its ability to fly since it adds weight, so maybe bees are just poor at balancing on top of a clump of dust.
It might still be worth considering as to whether the bee is just playing around (note that bumble bees in genus Bombus can allegedly play with balls) or is trying to do something directly beneficial for its survival. The fact the bee kept returning meant that it might enjoy collecting the dust as a form of play or see another benefit.
Honey bees are attracted to fresh sawdust, and common hypotheses (not tested, so I can’t be sure if they’re true) are:
My additional guess is that the carpenter bee is trying to keep house. To make the space clean and ready for more excavation or prepare the box for its brood, it needs to push the dust out of the nest. Dust is less dense than wood, so some of it has to be moved out. Even if there’s a lot of space (nest boxes are quite spacious), the bee might instinctively gather and eject the dust.
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Ok, this is so cool, and the fact that Bombus species play makes me love them even more.
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I don’t know exactly what is happening here, but I doubt the information about honeybees is particularly relevant.
Carpenter bees use sawdust as partitions for their nest cells. Many solitary bee species also plug the entrance to their nests with some kind of material, though the carpenter bees around here seem to leave the cavities open (they also don’t seem to be particularly interested in tidiness, judging by the piles of sawdust they leave lying around).
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